Conventional circular knitting machines generally include sinkers driven by a cam. The cam has a driving path to move the sinkers to and fro to perform a knitting operation.
The sinker is engaged with a preset driving path, as shown in FIG. 1. During a knitting operation, the lug 62 of the sinker 61 is engaged with the driving path 64 of the cam 63 so that the sinker 61 is moved according to the driving path 64, to perform knitting operation. The cam 63 is mounted horizontally on the machine deck. The sinker 61 also is mounted horizontally.
The sinker 61 is located on a sinker drum 60 which rotates at high speed during knitting operation, and the sinker 61 is driven by the driving path 64 to move reciprocally to and fro rapidly. When the sinker drum 60 rotates at high speed, the sinker 61 is moved outwards at a great centrifugal force. Hence the lug 62 of the sinker 61 does not move smoothly in the driving path 64.
To remedy the foregoing problems, Applicant has proposed an improved design that includes a sinker drum with a slanted surface so that the cams and sinkers are mounted at an inclined angle against the horizontal surface of the machine deck. The sinkers may be moved in an inclined manner in the sinker troughs of the sinker drum and therefore may be driven by the cams more smoothly.
Although the slanted installation set forth above can reduce the centrifugal force of the sinker that hits the cam and therefore increase the service life of the sinker and the cam, it creates other problems. First, with the sinker directly mounted on the sinker drum in an inclined manner, the surface for holding formed yarn laps on its throat portion is also inclined. As a result, the formed yarn laps tend to slip downwards and stretch the yarn coupled on the needle. Second, with the sinker inclined, the movement of the sinker in the sinker trough is also inclined. As a result, the sinker is prone to hit the yarn feeding plate. The circular knitting machine could therefore become inoperable. The present invention aims to improve these problems.